/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.neo4j.cypher.internal.runtime

class SelectivityTrackerRegistrator() {
  private var count: Int = 0

  def register(): Int = {
    val trackerIndex = count
    count += 1
    trackerIndex
  }

  def result(): QuerySelectivityTrackers = new QuerySelectivityTrackers(count)
}

class QuerySelectivityTrackers(trackersCount: Int) {

  def initializeTrackers(): SelectivityTrackerStorage = {
    new SelectivityTrackerStorage(trackersCount)
  }
}

class SelectivityTrackerStorage(trackersCount: Int) {

  private val trackers: Array[SelectivityTracker] =
    Array.fill[SelectivityTracker](trackersCount)(null)

  def get(trackerIndex: Int, predicatesCount: Int): SelectivityTracker = {
    var t = trackers(trackerIndex)
    if (t eq null) {
      t = new SelectivityTracker(predicatesCount)
      trackers(trackerIndex) = t
    }
    t
  }
}
